Supersensitization of silver halide photothermographic emulsions

Abstract

Supersensitization of photothermographic silver halide emulsions is effected by the addition of a metal chelating agent to a photothermographic emulsion which is or becomes spectrally sensitized.

What is claimed is: 
     
       1. A spectrally sensitized silver halide photothermographic emulsion layer comprising a reducible silver source material as 20 to 70% by weight of said emulsion layer, photosensitive silver halide, and a reducing agent for silver ion, said silver halide having no latent image therein and being present as 1.5 to 7.0% by weight of said emulsion layer and said emulsion layer having a speed increasing effective amount of a metal complexing agent therein in an amount equal to 0.4 to 40% by weight of total silver in said emulsion. 
     
     
       2. The emulsion of claim 1 wherein said complexing agent is an amine-type acetic acid compound, ester compounds thereof, or alkali metal salt thereof. 
     
     
       3. The emulsion of claim 2 wherein said amine-type acetic acid compounds are present in a range bewteen 0.4 and 40% by weight of total silver in said emulsion and are represented by any of the formulae:  wherein R 1  through R 4 , R 8  through R 16 , which can be the same or different, each represents a hydrogen atom, an alkali metal atom, aryl group, or an alkyl group, and R 5  -R 7 , which can be the same or different, each represents a hydrogen atom, an alkyl group or an acetic acid group as shown below   --CH.sub.2 COOR.sub.1     wherein R 1  is defined above, and n represents an integer of 1 or greater.   
     
     
       4. The emulsion of claim 1 wherein said metal complexing agent was added after spectral sensitization. 
     
     
       5. The emulsion of claim 2 wherein said metal complexing agent was added after spectral sensitization. 
     
     
       6. The emulsion of claim 3 wherein said metal complexing agent was added after spectral sensitization. 
     
     
       7. The emulsion of claim 1 containing a sensitizing dye represented by the formulae: ##STR12## wherein R 17  and R 18 , which may be the same or different, each represents 1) an alkyl group (containing 1 to 8 carbon atoms, or 2) a substituted alkyl group containing 6 or less carbon atoms substituted by a substituent selected from the group consisting of a carboxy group, a sulfo group, a cyano group, a halogen atom, a hydroxy group, an alkoxycarbonyl group (containing 8 or less carbon atoms), an alkoxy group (containing 7 or less carbon atoms), an aryloxy group, an acyloxy group containing 3 or less carbon atoms, an acyl group containing 8 or less carbon atoms, a carbamoyl group, a sulfamoyl group, and an aryl group, or the like, provided that the alkyl group may be substituted by two or more of these substituents, R 19  represents a hydrogen atom, a lower alkyl group containing 5 or less carbon atoms, a phenyl group or a benzyl group, a halogen atom, a hydroxyl group, a carboxyl group or an acyloxy group shown below by the formula ##STR13##  wherein R 20  represents an alkyl group having 1 to 5 carbon atoms, or an unsubstituted or substituted phenyl group,   D represents the non-metallic atoms necessary for completing a 6-membered ring containing three methylene units, which ring may be substituted by an alkyl group containing 8 or less carbon atoms, including a ring of the formula: ##STR14## wherein R' and R" each represents a hydrogen atom, or an alkyl group (substituted or not) containing 8 or less carbon atoms,   E represents the non-metallic atoms selected from C, N, S, O and Se necessary for completing a 5-membered ring wherein R 21  and R 22 , which can be the same or different, each represents a hydrogen atom, an alkyl group or a phenyl group,   Z 0  and Z 1  each represents non-metallic atoms necessary for completing a 5- or 6-membered, nitrogen-containing heterocyclic ring selected from the group consisting of (a) a thiazole nucleus including benzothiazole, naphthothiazole, 4-chlorobenzothiazole, 5-chlorobenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, 5-methylbenzothiazole, 6-methylbenzothiazole, 5-bromobenzothiazole, 6-bromobenzothiazole, 5-iodobenzothiazole, 5-phenylbenzothiazole, 5-methoxybenzothiazole, 6-methoxybenzothiazole, 5-ethoxybenzothiazole, 5-carboxybenzothiazole, 5-ethoxycarbonylbenzothiazole, 5-phenethylbenzothiazole, 5-fluorobenzothiazole, 5-trifluoromethylbenzothiazole, 5,6-dimethylbenzothiazole, 5-hydroxy-6-methylbenzothiazole, tetrahydrobenzothiazole, 4-phenylbenzothiazole, naphthol[2,1-d]thiazole, naphtho[1,2-d]thiazole, naphtho[2,3-d]thiazole, 5-methoxynaphtho[1,2-d]thiazole, 7-ethoxynaphtho[2,1-d]thiazole, 8-methoxynaphtho[2,1-d]thiazole, 5-methoxynaphtho[2,3-d]thiazole, (b) a selenazole nucleus, including benzoselenazole, 5-chlorobenzoselenazole, 5-methoxybenzoselenazole, 5-methylbenzoselenazole, 5-hydroxybenzoselenazole, naphtho[2,1-d]selenazole, naphtho[1,2-d]selenazole, (c) an oxazole nucleus, including benzoxazole, 5-chlorobenzoxazole, 5-methylbenzoxazole, 5-bromobenzoxazole, 5-fluorobenzoxazole, 5-phenylbenzoxazole, 5-methoxybenzoxazole, 5-trifluorobenzowazole, 5-hydroxybenzoxazole, 5-carboxybenzoxazole, 6-methylbenzoxazole, 6-chlorobenzoxazole, 6-methoxybenzoxazole, 6-hydroxybenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5-ethoxybenzoxazole, naphtho[2,1-d]oxazole, naphtho[1,2-d]oxazole, naphtho[2,3-d]oxazole, (d) a quinoline nucleus, including 2-quinoline, 3-methyl-2-quinoline, 5-ethyl-2-quinoline, 6-methyl-2-quinoline, 8-fluoro-2-quinoline, 6-methoxy-2-quinoline, 6-hydroxy-2-quinoline, 8-chloro-2-quinoline, 8-fluoro-4-quinoline, (e) a 3,3-dialkylindolenine nucleus, including 3,3-dimethylindolenine, 3,3-diethylindolenine, 3,3-dimethyl-5-cyanoindolenine, 3,3-dimethyl-5-methoxyindolenine, 3,3-dimethyl-5-methylindolenine, 3,3-dimethyl-5-chloroindolenine, (f) an imidazole nucleus, including 1-methylbenzimidazole, 1-ethylbenzimidazole, 1-methyl-5-chlorobenzimidazole, 1-ethyl-5-chlorobenzimidazole, 1-methyl-5,6-dichlorobenzimidazole, 1-ethyl-5,6-dichlorobenzimidazole, 1-alkyl-6-methoxybenzimidazole, 1-methyl-5-cyanobenzimidazole, 1-ethyl-5-cyanobenzimidazole, 1-methyl-5-fluorobenzimidazole, 1-ethyl-5-fluorobenzimidazole, 1-phenyl-5,6-dichlorobenzimidazole, 1-allyl-5,6-dichlorobenzimidazole, 1-allyl-5-chlorobenzimidazole, 1-phenylbenzimidazole, 1-phenyl-5-chlorobenzimidazole, 1-methyl-5-trifluoromethylbenzimidazole, 1-ethyl-5-trifluoromethylbenzimidazole, 1-ethylnaphtho[1,2-d]imidazole, (g) a pyridine nucleus, including pyridine, 5-methyl-2-pyridine, 3-methyl-4-pyridine) and a merocyanine nucleus,   X represents an acid anion, including but not limited to a halide ion (e.g., Cl - , Br -  or I - ), perchlorate ion, sulfamate, thiocyanate ion, acetate ion, methylsulfate ion, ethylsulfate ion, benzenesulfonate ion, toluenesulfonate ion, and   m represents 0, 1, 2 and 3.   
     
     
       8. The emulsion of claim 7 wherein said complexing agent is an amine-type acetic acid compound, ester compounds thereof, or alkali metal salt thereof. 
     
     
       9. Teh emulsion of claim 7 wherein said amine-type acetic acid compounds are present in a range between 0.4 and 40% by weight of silver in said emulsion and are represented by any of the formulae: ##STR15## wherein R 1  through R 4 , R 8  through R 16 , which can be the same or different, each represents a hydrogen atom, an alkali metal atom, aryl group, or an alkyl group, and R 5  -R 7 , which can be the same or different, each represents a hydrogen atom, an alkyl group or an acetic acid group as shown below   --CH.sub.2 COOR.sub.1     wherein R 1  is defined above, and n represents an integer of 1 or greater.   
     
     
       10. The emulsion of claim 9 wherein said metal complexing agent was added after spectral sensitization. 
     
     
       11. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 1. 
     
     
       12. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 2. 
     
     
       13. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 3. 
     
     
       14. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 7. 
     
     
       15. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 8. 
     
     
       16. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 9. 
     
     
       17. A photothermographic element comprising a support layer having on at least one surface thereof at least one photothermographic emulsion according to claim 10. 
     
     
       18. The photothermographic emulsion of claim 1 wherein said reducing agent for silver ion comprises a leuco dye reducing agent present in sufficient quantity to generate a visible color image. 
     
     
       19. The photothermographic emulsion of claim 3 wherein said reducing agent for silver ion comprises a leuco dye reducing agent present in sufficient quantity to generate a visible color image. 
     
     
       20. The photothermographic emulsion of claim 7 wherein said reducing agent for silver ion comprises a leuco dye reducing agent present in sufficient quantity to generate a visible color image. 
     
     
       21. The emulsion of claim 1 wherein said silver halide is the reaction product of a halide salt and said silver source material.-- 
     
     
       22. The emulsion of claim 2 wherein said silver halide is the reaction product of a halide salt and said silver source material and said metal complexing agent is present as from 0.6 to 35% by weight of total silver in said emulsion. 
     
     
       23. The emulsion of claim 3 wherein said silver halide is the reaction product of a halide salt and said silver source material.-- 
     
     
       24. The emulsion of claim 7 wherein said silver halide is the reaction product of a halide salt and said silver source material and said metal complexing agent is present as from 0.6 to 35% by weight of total silver in said emulsion. 
     
     
       25. The emulsion of claim 9 wherein said silver halide is the reaction product of a halide salt and said silver source material.